[2.7] bpo-35133: Fix mistakes when concatenate string literals on different lines. (GH-10284) (GH-10335) (GH-10336)

Two kind of mistakes:

1. Missed space. After concatenating there is no space between words.

2. Missed comma. Causes unintentional concatenating in a list of strings.
(cherry picked from commit 34fd4c2019)
(cherry picked from commit 7054e5c80b)

Lib/idlelib/idle_test/htest.py

@@ -329,7 +329,7 @@ _undo_delegator_spec = {
 _widget_redirector_spec = {
     'file': 'WidgetRedirector',
     'kwds': {},
-    'msg': "Every text insert should be printed to the console."
+    'msg': "Every text insert should be printed to the console "
            "or the IDLE shell."
     }
 

Lib/test/test_compile.py

@@ -392,7 +392,7 @@ if 1:
             'from sys import stdin)',
             'from sys import stdin, stdout,\nstderr',
             'from sys import stdin si',
-            'from sys import stdin,'
+            'from sys import stdin,',
             'from sys import (*)',
             'from sys import (stdin,, stdout, stderr)',
             'from sys import (stdin, stdout),',